The present invention relates to LCD display substrates and methods for manufacturing them. More particularly, the present invention relates to display substrates that improve display aperture ratio and methods for manufacturing such substrates.
A typical LCD array substrate includes respective pluralities of respectively parallel gate lines and data lines that intersect but are electrically insulated from each other, and a plurality of generally rectangular pixels defined by the intersecting gate and data lines. A storage line, a switching element and a pixel electrode are formed in each pixel. The storage lines are formed in the same layer as the gate lines. The switching element is connected to an associated gate line and an associated data line. The pixel electrode receives a pixel voltage from the switching element.
An insulative passivation layer is formed between the switching element and the pixel electrode, and a thick organic insulation layer is optionally formed on the passivation layer to planarize the surface of the substrate. A first hole is formed through the passivation layer and the organic insulation layer to partially expose an output terminal of the switching element, and the output terminal and the pixel electrode are electrically connected to each other through the first hole.
A second hole is formed through the organic insulation layer in an area corresponding to the storage line to reduce the spacing between the storage line and the pixel electrode so as to enable an associated storage capacitor to be charged easily.
In order to precisely locate the first hole over the output terminal of the switching element, the area of the output terminal has to provide a marginal area that is sufficiently large as to prevent any mismatch between the two features. Similarly, to precisely locate the second hole over the storage line, the area of the storage line must also provide a marginal area that is sufficiently large to prevent any mismatch. As a result, when display substrates employ an organic insulation layer, the aperture ratio of each pixel may be undesirably reduced.